Webplayer sandbox security policy: When do I prefetch security policy?

The documentation states:

A Unity webplayer needs a socket served policy in order to connect to a particular host. This policy is by default hosted by the target host on port 843 but it can be hosted on other ports as well. The functional difference with a non-default port is that it must be manually fetched with Security.PrefetchSocketPolicy() API call and if it is hosted on a port higher than 1024 the policy can only give access to other ports higher than 1024.

The question: how do I prefetch the socket policy? Do I do it in the void Update () {...}?